X-ray sensitive camera comprising two image receivers and x-ray device

ABSTRACT

The invention relates to an X-ray sensitive camera ( 1, 55 ) comprising a first X-ray sensitive image receiver ( 4 ), for creating a first tomogram with a first depth of field profile, in addition to a second X-ray sensitive image receiver ( 5 ) for creating a second tomogram with a second depth of field profile. The invention also relates to an X-ray device comprising an image receiver ( 4, 5 ) that is contained in an X-ray sensitive camera ( 55 ), in addition to an X-ray emitter ( 52 ) with a primary diaphragm ( 57 ) and adjusting means ( 43, 44 ) for the image receiver and/or X-ray emitter and/or primary diaphragm and/or a combination thereof. The camera is equipped with a second image receiver ( 5 ), which can be brought into the beam path ( 54 ) of the X-ray emitter using the adjusting means ( 43, 44 ).

The invention relates to an X-ray sensitive camera comprising an X-raysensitive image detector for creating a first tomographic image with afirst depth of focus profile and to an X-ray system comprising such acamera.

Such a camera is used for the creation of dental panoramic tomographicimages by means of X-ray apparatus.

The depth of focus is determined by the resolution just acceptable inthe X-ray image to be created, there being a smooth transition from “infocus” (maximum resolution) to “out of focus”. This phenomenon ofsmudging is well known and is based substantially on the speed of theX-ray fan beam on the one hand and the speed of the film or its digitalcounterpart on the other hand.

DESCRIPTION OF THE RELATED ART

A dental X-ray diagnostic device for producing panoramic tomographicimages of a patient's jaw is disclosed in EP 0 229 971. In addition topanoramic tomographic images (PAN images), images of one or moreuser-defined, selectable jaw sections can be produced in a plurality ofsuperposed layers (multilayer images). Furthermore, a film cassetteholder is mounted on a rotatable unit bearing the X-ray emitter so thatit can be pivoted from an operating position to a non-operatingposition, which makes it possible to produce teleradiographic images(ceph images), as the X-ray emitter can then direct a beam unhinderedpast the film cassette holder.

An X-ray diagnostic device for the production of X-ray images of partsof a patient's body is disclosed in EP 0 632 994 A1, in which there is aline detector camera with an X-ray detector, the width of whichcorresponds to the width or the length of the body part to be imaged.The line detector camera can be moved together with the X-ray sourcealong the part of the body to be imaged via regulating means. The X-raydiagnostic device can thus be configured to produce a PAN image as wellas a teleradiographic image (ceph image), and the line detector camerafor producing the required image can be unplugged and replugged, forwhich purpose it is equipped with a connector containing connectingmeans for a detachable mechanical and electrical connection with aholder. Furthermore, various possibilities are disclosed for aiming theX-ray fan beam when producing the teleradiographic image using a movableemitter or a primary diaphragm or a combination of the two.

A camera that is capable of being unplugged and replugged is describedin detail in EP 0 634 671 A1, particular attention being paid to thedetachable mounting of the camera on a holder.

A detector system for the production of X-ray images is disclosed in EP0 858 773 A2 and consists of detectors having dimensions similar tothose of the detector of an intraoral sensor. The detector system is soconstructed that transversal slice acquisition images (TSA images) maybe produced and the detector system mounted for displacement along itslongitudinal axis inside the line detector camera. The detector elementscan be displaced along the main axis of the detector by adjustmentmeans.

The sensors used in EP 0 858 773 A2 to produce a PAN or a ceph imagetypically have an image height of from 135 to 180 mm and an image widthof approx. 6 mm. The sensors used to produce TSA images typically havedimensions of about 30×20 mm. The difference in width results from thefact that, in the case of a PAN image, it is desirable for the layerthickness (depth of focus) of the sharp slice to be at least the same asthe thickness of the object being imaged, whereas, by contrast, thelayer thickness (depth of focus) of the sharp image in the case of a TSAimage is about 1 to 3 mm.

However, the reduced layer thickness and the reduced depth of focus mustnecessarily require an increase in the width of the image detector usedfor the creation of images with a CCD sensor operating in TDI mode. Thesame applies to image detectors that produce individual plane imagesthat are subsequently computed to a tomographic image showing therequired depth of focus. CMOS detectors exemplify image detectors ofthis type.

Although prior art technology already provides for the camera used forthe creation of a panoramic image to be unplugged and then replugged forthe production of a ceph image, for the purpose of producing a TSA imagean additional X-ray system is still required which provides the sensordimensions necessary for this purpose.

SUMMARY AND OBJECTS OF THE INVENTION

According to the invention, an X-ray-sensitive camera is proposed whichhas a first X-ray-sensitive image detector for creating a firsttomographic image having a first depth of focus profile. Furthermore, asecond X-ray-sensitive image detector for the creation of a secondtomographic image with a second depth of focus profile is provided.

This camera is thus suitable for the creation of different types oftomographic images.

According to a first development, the second depth of focus profile issmaller than the first depth of focus profile. Such a camera istherefore suitable not only for the creation of panoramic tomographicimages but also for the creation of lateral or transverse tomographicimages, usually designated as multilayer images. The invention thusmakes it possible to create PAN or TSA images with one and the samecamera.

According to another development, the image-detecting active surface ofthe second image detector can be at least twice as large as the firstimage detector, in a first dimension. Furthermore, the second imagedetector may be not more than half as large as the first image detector,in a second dimension. The advantage of this is that, on the one hand,existing elongated line sensors having dimensions suitable for PAN orceph images and, on the other hand, existing face sensors having therequired width for intraoral images can be used as image detectors. Itis not necessary to provide a PAN sensor having a width sufficient forthe production of TSA images, which would cost considerably more thanthe two individual sensors together.

According to another development, the image detectors are installed in acommon casing with the camera.

The second image detector is advantageously mounted alongside the firstimage detector. The shoulder freedom of the patient to be X-rayed isthus not impaired by the camera.

The second image detector is advantageously mounted on the rear side ofthe first image detector. Such a camera can be built into traditionalX-ray systems for the production of PAN images and thus provides theoption of retrofitting for the production of multilayer images,especially if it is possible, for example, to unplug the camera, turn itaround relatively to the X-ray emitter, and replug it.

The camera is advantageously designed so that the second image detectorcan be retrofitted. In this case it is possible to first equip the X-raysystem with a camera for the production of PAN images and then, whennecessary, install the second image detector in the camera for theproduction of multilayer images.

According to another development, the second image detector is part ofthe first image detector or vice versa. On the one hand, this allows theimage-detecting surface provided by the second image detector to be usedeven if no images typical for this type of detector are being produced,and, on the other hand, it allows part of the first image detector to beused for the production of the image using the second image detector.

According to another development, adjustment means are provided to bringeither the first or the second image detector, as desired, into properalignment with an X-ray emitter for the production of the respectiveX-ray image.

The adjustment means and both image detectors can be built into a commoncasing with the camera or on the camera casing and in the region ofconnecting means for mounting the camera on a support, and the camera inits entirety is then adjustable relatively to said connecting means. Inthe latter case it is also easy to regulate positioning of the cameravisually from outside and confirm that the correct sensor has been movedinto the proper position for creation of the image. Furthermore, thecamera casing can be kept more compact than when the sensor adjustmentmeans are disposed only within the camera casing.

If the camera has a radiolucent region, it is possible to leave thecamera in the X-ray fan beam for the creation of an additional imagewithout any significant negative impact on the image production. Thecamera can therefore remain in place and need not be removed.

According to one development, the radiolucent region is located betweenthe first and second image detectors.

According to another development, the radiolucent region is locatedalongside the first and second image detectors.

The invention also relates to an X-ray system having an image detectorbuilt into an X-ray-sensitive camera, which system also comprises anX-ray emitter having a primary diaphragm and adjustment means for theimage detector and/or the X-ray emitter and/or the primary diaphragmand/or combinations thereof. Within the camera there is provided asecond image detector, and the second image detector is capable of beingmoved into the optical path of the X-ray emitter by means of theadjustment means.

Using such an X-ray system, it is possible, without changing the camera,to create, say, both panoramic tomographic images and multilayer images,provided the second image detector is appropriately constructed.Advantageously, the camera and the X-ray emitter used for this purposeare mounted on a common support, as is well known in X-ray systemsadapted for the creation of panoramic tomographic images.

Advantageously, adjustment means are provided which cooperate with thecamera, which adjustment means can be built into the camera casing orbuilt into connecting means between the camera and the support ormounted on the support itself.

Adjustment means disposed inside the casing are shielded from outsideinfluences. There is relatively more space available when the adjustmentmeans are mounted on the support, and the camera can be made smaller andlighter.

The adjustment range of the camera is equal to at least one width of thefirst sensor so that the latter can be moved completely away from theoptical path of the X-ray fan beam when an image is to be created usingthe second image detector.

The X-ray system can, in a development, be additionally equipped with adevice for the production of teleradiographic images using an additionalimage detector. When the X-ray emitter is aligned to produce such a cephimage, the camera is disposed in the region of the path of radiationbetween the X-ray emitter and the image detector of the device for theproduction of the ceph image, and in this region the camera isradiolucent.

Alternatively, the path of adjustment can be dimensioned such that whenthe X-ray emitter is aligned for the purpose of creatingteleradiographic images, the camera can be moved outside the path ofradiation between the X-ray emitter and the image detector of the devicefor the creation of teleradiographic images.

Both methods have the advantage of not requiring manual intervention forswitching the imaging method from close-up tomographic images (PAN/TSA)to teleradio-graphic images (ceph images).

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is illustrated in the drawings,in which:

FIGS. 1 a and 1 b show a camera with two different image detectorslocated adjacent to each other,

FIGS. 2 a and 2 b show a camera with two different sensors that areoriented back to back,

FIGS. 3 a to 3 d show various configurations of two image detectors,which together form a single detector,

FIGS. 4 a and 4 b show a first and second adjustment mechanism for thedisplacement of the sensors within a camera casing or for thedisplacement of the camera housing,

FIG. 5 a shows a diagram of an X-ray system of the invention for theproduction of PAN and TSA images in a first imaging situation (PAN),

FIG. 5 b shows the X-ray system of FIG. 5 a in a second imaging position(TSA),

FIG. 5 c shows an additional X-ray system having a third imagingposition (ceph),

FIG. 5 d shows an additional X-ray system having an adjustable primarydiaphragm for three imaging positions,

FIGS. 5 e and 5 f are diagrams illustrating various imaging situations,and

FIG. 6 is a further diagram illustrating an eccentrically pivotedcamera.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

A camera 1 of the invention is illustrated in FIG. 1 a in a perspectiveview. Camera 1 has a casing 2 in which a circuit board 3 is installed. Afirst image detector 4 in the form of a line sensor is provided on board3, which detector is a CCD sensor in this exemplary embodiment and has alength which is many times greater than its width.

The image detector 4 can be divided into an image detecting area in theform of a CCD sensor 4.1 and read-out electronics 4.2. Such forms of animage detector are well known in the prior art. In principle, imagedetectors such as CMOS sensors that produce individual images in theform of a plane image can also be used.

Adjacent to the first image detector 4 there is provided an additionalimage detector 5, which is again divided into an image-detecting zone5.1 in the form of a CCD sensor and a read-out zone 5.2 and which islikewise mounted on support 3.

Casing 2 is equipped with mechanical and electrical connecting means 6,7 so that camera 1 can be mounted on a standard support structure (notshown).

A cross section through the camera 1 taken along the line 1 b-1 b inFIG. 1 a is illustrated in FIG. 1 b. Board 3 with the first imagedetector 4 and the second image detector 5 is shown in casing 2, and thesecond image detector 5 is installed in a holding device 8 on board 3.

FIG. 2 a shows a camera 21, which likewise has a casing 2 and a board 3,and the first image detector 4 is mounted on board 3. The second imagedetector 5, represented by dashed lines, is mounted on the rear side ofboard 3.

In order to ensure electrical contact when the camera 21 is rotated, theelectrical contact 7 is duplicated as 7.1 and 7.2. This double contactcan obviously also be provided on means (not shown) for coupling thecamera to an X-ray system.

When the camera is rotated as in FIG. 6, a connection that can beunplugged is not required. This rotation can be achieved by a motor ormanually.

The cross-sectional illustration of FIG. 2 b clearly shows theback-to-back arrangement of the two image detectors 4, 5, that is, oneither side of support 3. Image detector 5 is installed in the holdingdevice 8.

FIGS. 3 a to 3 d show different embodiments of an image detector forminga “virtual” combination of the two image detectors 4, 5 present. Thevirtual image detector 31 can be designed such that the length of theline detector of image detector 4 is increased by the required amount(see FIGS. 3 a to 3 c). The virtual image detector 31 can alternativelybe designed such that the image detector 4 in the form of a linedetector increases the width of image detector 5 in the form of a facesensor (see FIG. 3 d).

In all cases care must be taken to ensure that the direction of motionof the charges on image detector 4 carrying the image signals in TDImode is made to comply with the direction of motion of the charges onimage detector 5, as indicated by the arrows.

Of course, it must be ensured that appropriate corrective measures areeffected in the transition region between the two image detectors 4, 5,in order to compensate for image distortions. Such corrections can befixed or variable by appropriate circuitry or they can be subsequentlyeffected using appropriate correction methods.

Since an X-ray system for the production of a PAN image will beconsidered to be the basic device on account of the fact that suchimages are produced more frequently, the camera can be designed so thatthe image detector 5 for the TSA image can be retrofitted. Retrofittingcan be carried out, for example, by opening the casing and plugging inthe image detector 5 in an appropriate place and making any additionalnecessary electrical or mechanical connections.

Prior art X-ray systems for the production of PAN images have fixedconnecting means between the X-ray emitter on the one hand and thedetector on the other hand so that both are moved together as a unit. Asa rule, the detector as such is fastened rigidly to the common supporttogether with the X-ray emitter.

A first and second adjustment mechanism for positioning the imagedetectors are illustrated in FIGS. 4 a and 4 b. The camera 41, which isattached to a support structure 40, has a casing 42, in which the imagedetectors 4, 5 are guided by an adjustment mechanism in the form of acarriage 43 on a guide track 44. The image detectors 4, 5 can thus bemoved with the carriage 43 and the adjustment mechanism 44 from theposition illustrated to the dashed line position 4′, 5′, so that insteadof the face sensor of the image detector 5, the line detector of imagedetector 4 moves into the X-ray fan beam represented by the line 45.

In FIG. 4 b, the adjustment mechanism is located between a camera 41 andthe support 40. Camera 41 is mounted via its casing 42 on the supportstructure 40 for displacement thereon, as represented by carriage 43attached to the camera and guide track 44 attached to the support 40.This allows the entire camera 41 to be moved from the positionillustrated to the position represented by the dashed line, so that theX-ray beam, again illustrated by line 45, is aligned not with imagedetector 5 but with image detector 4.

Camera 41 is attached by connecting means and these connecting means canalso include adjustment means. This, however, is not illustrated.

Alternatively, a TSA image can be produced with a motor-driven cameraholder, in which the sensor is positioned according to the desired modeof operation. The motor-driven camera holder forms the connectionbetween the connecting means of the camera and the support. Said holdercan be designed so that the camera plus connecting means can be movedalong a guide track or pivoted by means of a pivoting mechanism. Thusthe camera can be moved automatically into the optimal position in thesystem. A direct image series for a PAN image followed by a multilayerimage can be produced in this manner without any additional interventionon the part of the operator.

Main parts of an X-ray system 50 are illustrated in FIG. 5 a,specifically an imaging device with an imaging unit 51 and an X-rayemitter 52, in which the object to be examined in the form of apatient's head is positioned between the X-ray emitter 52 and theimaging unit 51. For the production of a panoramic tomographic image,the X-ray beam 54 emitted from the X-ray emitter 52 is directed to theimage detector 4 constructed in the form of a line detector, so that therequired length for producing a PAN image of the upper and lowerjawbones is provided. The detecting unit 51 and X-ray emitter 52 aremounted on a common support and are adapted for movement around at leastpart of the object to be examined.

Meanwhile, the image detector 5 in the form of a face sensor is in aneutral position outside the X-ray beam 54.

An imaging situation for producing a multilayer image of a specificsubregion of the jawbone, such as a single tooth, is illustrated in FIG.5 b. The camera disposed on the imaging unit 51 is now aligned so thatthe image detector 5 is exposed to the X-ray beam 54, and the imagedetector 4 is now in a neutral position.

Accordingly, in the case of a camera having a sensor configuration as inFIGS. 2 a and 2 b, either the image detector 4 or the image detector 5will be oriented toward the X-ray emitter. For this purpose, the cameracan either be unplugged and replugged or automatically rotated by amotorized adjustment mechanism.

Obvious to the person skilled in the art, but not always illustrated inthe figures, is the use of a primary diaphragm with mechanically rigiddefault orifices or an orifice that can be regulated by moveablebeam-delimiting elements (not shown) for restricting the extent of theX-ray beam, the extent of the X-ray beam being such that itsubstantially matches the image-sensitive area of the image detector 4or 5 or even perfectly fits the image-sensitive surfaces of the imagedetectors 4 and 5 respectively, in accordance with the relevantstandards. Radiation bombardment by X-rays not needed for the productionof the image is thus avoided.

A diagram illustrating the production of a ceph image is shown in FIG. 5c.

A ceph image can be produced in an X-ray system equipped with a PAN unit“A” and a ceph unit “B” by bringing a separate camera 61, equipped withan image detector 62 with a line sensor of appropriate length for theproduction of the ceph image, into the ceph position. The camera 55 forthe production of the PAN image and the multilayer image is positionedso that the X-ray beam 54 emitted from the emitter 52 is directed pastthe casing of said camera 55.

If a separate ceph sensor is not provided, the first camera 55 can beunplugged and replugged manually if the image detector for theproduction of the PAN image located therein is also long enough to fitthe dimensions required to produce the ceph image.

An imaging unit 51 in which there is a radiolucent zone 56 between thetwo image detectors 4, 5 is illustrated in FIG. 5 d. The dimensions ofzone 56 are such that a fan beam 54 emitted by X-ray emitter 52 can passsubstantially unhindered through the camera.

The camera is stationary in this exemplary embodiment and the fan beam54.1-54.3 is aimed at the appropriate image detector 4, 5, 62 by anadjustable primary diaphragm 57. To this end, the geometric dimensionsof the primary diaphragm 57 are adjusted to the size of the image to beproduced. The width for the production of a PAN image is, say, 0.9 mm.

This principle is illustrated in detail in FIG. 5 e. The primarydiaphragm 57 here has two orifices that allow the passage of theappropriate fan beam 54.1, 54.2 for producing the different types ofimage. The other fan beam is obviously blocked during the production ofan image. The cone of radiation 58 produced by the X-ray emitter issufficiently large to provide the desired fan beam 54.1, 54.2 or, whenneeded, the fan beam for a teleradiographic image.

In lieu of splitting the fan beam 58 emitted from the X-ray emitter 52by an adjustable primary diaphragm, the X-ray emitter 52 can, ifdesired, be directed, by adjustment mechanisms, toward either one of theimage detectors 4, 5, as illustrated in FIG. 5 f. Such an adjustment isalready known for combined PAN/ceph devices. The adjustment may beachieved by sliding or, as illustrated, by pivoting. The advantagegained in this case is that the central ray of the X-ray fan beam 58always lies within the fan beam 54.

With the eccentric mounting of the camera 2 illustrated in FIG. 6, a PANimage can be produced in an initial alignment of the camera 2 in whichthe image detector 4 lies within the X-ray fan beam 54.1. With thisalignment of camera 2 it is also possible to produce a ceph image, asthe X-ray fan beam 54.3 is directed past camera 2. A multilayer imagecan be produced when camera 2 is in the position represented by thedashed lines, which is achieved by rotating it about the center ofeccentricity 59. In doing so, the image detector 4 is positioned closerto the X-ray fan beam 54.3 for the ceph image than the image detector 5.

The arrangement illustrated has the advantage that a short jib for theceph camera is sufficient for producing the ceph image, because theX-ray fan beam 54.3 stays close to the wall.

The following fundamental principle must be observed: a differentprimary diaphragm will be used for the production of a PAN image, amultilayer image, and a ceph image respectively and each image will becreated using only one imaging method. When several X-ray fan beams areillustrated together in the exemplary embodiments, this serves merely toclarify the geometric relationships. The primary diaphragm, however, isconstructed and adjusted such that the desired image detector isactivated by the correct X-ray fan beam for producing the desired image.

1-21. (canceled)
 22. An X-ray-sensitive camera comprising a firstX-ray-sensitive image detector for the creation of a first tomographicimage with a first depth of focus profile and a second X-ray-sensitiveimage detector for the creation of a second tomographic image with asecond depth of focus profile, wherein adjustment means are provided formoving, as desired, said first image detector or said second imagedetector into proper alignment with an X-ray emitter for the creation ofthe respective X-ray image.
 23. A camera as defined in claim 22, whereinthe second depth of focus profile is distinctly smaller than the firstdepth of focus profile.
 24. A camera as defined in claim 22, wherein theimage-sensitive active surface of said second image detector is at leasttwice as large as said first image detector, in a first dimension,and/or said second image detector is not more than half as large as saidfirst image detector, in a second dimension.
 25. A camera as defined inclaim 22, wherein the two image detectors are disposed in a commoncasing with said camera.
 26. A camera as defined in claim 22, whereinsaid second image detector is disposed alongside said first imagedetector.
 27. A camera as defined in claim 22, wherein said second imagedetector is disposed on the rear side of said first image detector. 28.A camera as defined in claim 22, wherein said second image detector isadapted for retrofitting.
 29. A camera as defined in claim 22, whereinsaid second image detector is part of said first image detector or saidfirst image detector is part of said second image detector.
 30. A cameraas defined in claim 29, wherein said adjustment means and the two imagedetectors are disposed in a common casing with said camera.
 31. A cameraas defined in claim 30, wherein said adjustment means are provided onsaid casing of said camera and in the region of connecting means for theattachment of said camera to a support and said camera can be adjusted,as an entity, relatively to said connecting means.
 32. A camera asdefined in claim 22, wherein said camera has a radiolucent zone.
 33. Acamera as defined in claim 32, wherein said radiolucent zone is disposedbetween said first image detector and said second image detector.
 34. Acamera as defined in claim 32, wherein said radiolucent region isdisposed alongside said first image detector and said second imagedetector.
 35. An X-ray system having an image detector built into anX-ray-sensitive camera further comprising an. X-ray emitter with aprimary diaphragm, a second image detector being provided inside saidcamera, wherein adjustment means are provided for moving, as desired,said first image detector or said second image detector into properalignment with an X-ray emitter for the creation of the respective X-rayimage.
 36. An X-ray system as defined in claim 35, wherein saidadjustment means are provided on said casing of said camera or inconnecting means disposed between said camera and a support or on saidsupport itself.
 37. An X-ray system as defined in claim 36, wherein theadjustment range of said camera is equal to at least one width of saidfirst sensor.
 38. An X-ray system as defined in claim 37, wherein thereis additionally provided an installation for the creation ofteleradiographic images with another image detector and, when said X-rayemitter is aligned for the purpose of creating a teleradiographic image,said camera is disposed in the region of the optical path between saidX-ray emitter and said image detector of said installation for thecreation of teleradiographic images and is radiolucent in said region.39. An X-ray system as defined in claim 38, wherein there isadditionally provided an installation for the creation ofteleradiographic images with another image detector and that the path ofadjustment is such that, when said X-ray emitter is aligned for thecreation of a teleradiographic image, said camera can be moved out ofthe optical path between said X-ray emitter and said image detector ofsaid installation for the creation of teleradiographic images.
 40. AnX-ray system as defined in claim 39, wherein said camera is mounted foreccentric adjustment and, in a first position, said image detector forthe creation of a first tomographic image is positioned in the path ofthe X-ray fan beam and, in a second position, said image detector forthe creation of a second tomographic image is positioned in the path ofthe X-ray fan beam.